Improvement in dividers



`tion of this invention.

UNITED STATES PATENT OFFICE..

S. ADDISON SHURTLEFF, OF TAUNTON, MASSACHUSETTS.

IMPROVEMENT IN DIVIDERS.

Specilieation forming part of Letters Patent No. 50,173, dated September 26, 1865.

To all whom it may concer/rt:

Beitknown that I, S. ADDrsoN SHURTLEEF, ot' Taunton, in the county ot' Bristol and State of Massachusetts, have invented a new and useful Improvement in Dividers; and I do hereby declare that the'ollowing is a full, clear, and exact description thereof, which will enable those skilled in the artto make and use the same, reference being had to the accompanying drawings, forming part of this specification, in which- Figure l represents a sectional front eleva- Fig. 2 is a transverse section of the same.

Similar letters of reference indicate corresponding parts.

This invention consists in combining with the ordinary legs of a pair of dividers a centering-leg, which passes down through the head ot' the dividers and is adiustablein a nut suspended by suitablelinks or toggle-arms from the ordinary legs in such a manner that said centering-leg can be adj usted up and down, according to the position of the main legs, and that bythe centering-leg the distance measured oft by the main legs can be divided off in two equal parts Without loss of time.

A represents the head of a pair of dividers, which forms the bearings for the pivot a, on which the two legs B B swing. In orderto keep these legs steady while they open and close, an arc, U, is secured to the leg B, and made to pass through a mortise in the leg B in `the usual manner. A screw, b, and spring b serve to give to the legs the nal adjustment after the same have been set and fastened by lhe set-screw c, passing through the leg B and bearing on the arc C. The head A is perforated with a round hole to receive the centering-leg D. The leg passes freely through the hole in the head, and it is provided with a screw-thread, e, which is tapped into a nut,f, and this nut is suspended from the main legs by means of two toggle-arms or links, g, as clearly shown in Fig. l of the drawings. The

links g connect to the main legs by means of pivots h, and to each other and to the nut f by the pivot t', and they are exactly equal in length, so the nut will always remain in the center between the main legs, Awhatever the position of the latter.

If it is desired to find the centerot'a certain distance or the middle of a line, the points of the main legs are placed in the ends ot' thc line and the centering-legl is screwed down untilits point strikes the surface on which the main legs rest. The indentation produced'by the point of the centering-leg indicates the correct center between the two indentatious made by the points of the main legs.

lt' the point of the centering-leg should be found to be not exactly ige; the center between the points ofthe main legs, the defect can he easily regulated by the nut and spring applied to one end ofthe arc O.

By theuse of my centering-dividers the workman is enabled to put the tool onto the work and nd the center instantly, thereby saving much time and labor; and, furthermore, the Work is done with great accuracy, and even a careless workman-cannot possibly miss the t center.

By raising the centering-leg my dividers can I.

nation with the main legs B B', substantially as and for the purpose described.

l 2. Passing the centerii'lg-leg through the head ofthe dividers, substantially as and for the purpose specified.

S. ADDISON SHURTLE FF.

Witnesses:

BERNARD A. GALLIGAN, C. H. KUKLAND. 

